Airway pressure release ventilation (APRV) enhances cardiac performance in patients with acute lung injury (ALI)/adult respiratory distress syndrome (ARDS)

Purpose

To determine whether APRV can safely enhance hemodynamics in patients with ALI/ARDS.

Methods

Patients with ALI/ARDS were ventilated in pressure control (PCV) with both upper and lower inflection points eliminated from the hysteresis curve; all patients had a pulmonary artery catheter. Ventilator settings achieved a pCO₂ of 35–45 torr and a pO₂ of > 60 torr. Patients were then changed to APRV. Data included: age, diagnosis, ventilator settings, hemodynamic profiles, ABG, lactate, and medications. Data (means ± SD) were compared using a Student's t-test; significance assumed for P < 0.05.

Results

Mean age was 58 ± 9 years (n = 12) and mean Lung Injury Score was 7.6 ± 2.1. Temperature (PCV 100.8 + 1 v APRV 100.6 + 1F; P > 0.5) and PaO₂/FIO₂ (PCV 168 ± 24 v APRV 182 ± 18; P > 0.0.5) were similar. Diagnoses were pneumonia (22%), abdominal sepsis (45%), trauma (33%), bacteremia (18%) and transfusion related lung injury (1%). Peak airway pressures fell from 38 ± 3 (PCV) 25± 3 cmH₂O(APRV, P < 0.05); mean pressures fell from 18 ± 3 (PCV) to 12 ± 2 cmH₂O (APRV; P < 0.05). Paralytic use (PCV 74% v APRV 4%; P < 0.05) and sedative use significantly declined (PCV 100% v. APRV 68%, P < 0.05). Pressor use decreased substantially (PCV 92% v ARPV 45%, P < 0.05). Lactate levels remained unchanged (PCV 2.2 ± 0.6 v APRV 1.8 ± 0.8 mmol/l; P > 0.05). Cardiac index rose from 3.2 ± 0.4 (PCV) to 4.6 ± 0.3 l/min/m² BSA (APRV; P < 0.05) while DO₂I increased by 36% (P < 0.05). CVP declined from 18± 4 (PCV) to 12± 5 cmH₂O (APRV; P > 0.05).

Conclusion

APRV may be used safely in patients with ALI/ARDS and decreases the need for paralysis and sedation compared to PCV. APRV increases cardiac performance with decreased pressor use and CVP in patients with ALI/ARDS. Further study of ARPV is warranted to discover its impact on resource utilization and patient outcome.